The invention relates to an apparatus for finding a parked vehicle again, as claimed in the preamble of patent claim 1.
The subject matter of the invention application is the relatively daily problem which occurs when someone has parked a vehicle in a large multistory car park and cannot find it again after visiting a supermarket, a cinema, after work or after traveling. A similar search can arise with car rental companies, company transport pools and large car workshops with a multistory car park.
Laid-open specification DE 10 2004 023 939 A1 describes a key for locking a lock, by means of which the lock can be found again after a relatively long time. The described key has a device for storage of the position of the lock, as well as an output apparatus for outputting the position. The position data is preferably determined using a global positioning system (GPS). A communication link with a satellite system must be ensured for this purpose.
DE 10111552 A1 discloses a mobile transponder which contains a GPS receiver by means of which this determines the position at which the transponder is located. Direction information is determined from the comparison of this position with the position of the vehicle, and is indicated.
DE 198 20 921 A1 discloses a mobile transponder for vehicles which receive a signal originating from the vehicle and use this to identify direction information about the location of the vehicle with respect to the mobile transponder. This direction information is indicated on a display in the mobile transponder.
Laid-open specification DE 34 39 644 A1 describes an altimeter for motor vehicles. The described altimeter has an air-pressure measurement device which supplies a corresponding electrical measured value, with this measured value being linked in an evaluation circuit with a reference variable that is stored in a memory, and with a drive signal, which corresponds to the current altitude value, being derived from this for a display unit. An altitude value that has been entered via a keyboard or the current altitude value most recently displayed on the display unit can be written as a reference variable to the memory, so that greater measurement accuracy can be achieved by repeated adjustment.
The object of the invention is to specify an apparatus for finding a parked vehicle again, which in particular makes it possible to find a floor level in a multistory car park or in an underground garage in which the vehicle is parked.
The invention achieves this object by the provision of an apparatus for finding a parked vehicle again, having the features of patent claim 1.
Advantageous embodiments and developments of the invention are specified in the dependent claims.
According to the invention, an apparatus for finding a parked vehicle again comprises a portable unit with a pressure sensor whose signals can be evaluated by an evaluation and control unit in order to determine the current air pressure, with the evaluation and control unit evaluating the determined air pressure in order to determine altitude, and storing a first air pressure value as a reference value at a predeterminable first time which reference value represents an instantaneous altitude of a geographic position of the parked vehicle. The evaluation and control unit estimates a height difference between a current geographic position of the portable unit and the geographic position of the parked vehicle at a second time, and/or continuously from a pressure difference between the determined current air pressure value and the reference value. The apparatus according to the invention advantageously makes it possible to determine the floor level in a multistory car park and/or in an underground garage in which the vehicle being looked for is parked. Furthermore, the apparatus according to the invention can be implemented at low cost and in a physically small manner by the use of appropriate pressure sensors.
In a refinement of the apparatus according to the invention for finding a parked vehicle again, a vehicle-end unit is provided with a pressure sensor whose signals can be evaluated by a vehicle-end evaluation and control unit in order to determine the current air pressure. The vehicle-end evaluation and control unit evaluates the determined air pressure in order to determine the altitude, and stores a first air pressure value as a reference value, relating to the predeterminable first time, which reference value represents the instantaneous altitude of the geographical position of the parked vehicle. A communication path is advantageously set up between a portable unit in the vehicle in order to interchange information between a communication unit and the portable unit and a vehicle-end communication unit.
In a further refinement of the apparatus according to the invention for finding a parked vehicle again, the portable unit and the vehicle-end unit are matched to one another via the communication path at the first time such that the same first air pressure value is stored as the reference value at the first time in the evaluation and control unit in the portable unit and in the vehicle-end evaluation and control unit. The evaluation and control unit in the portable unit receives the reference value, which is stored in the vehicle-end evaluation and control unit, at the second time via the communication path to determine the altitude difference. The vehicle-end evaluation and control unit can update the first air pressure value stored as the stored reference value as required and/or continuously by renewed evaluation of the signals from the vehicle-end pressure sensor. This makes it possible to compensate in an advantageous manner for weather-dependent air pressure fluctuations in the altitude determination.
In a further refinement of the apparatus according to the invention, the evaluation and control unit in the portable unit determines a floor-level difference in a multistory car park from the altitude difference determined at the second time, and emits the determined altitude difference. The evaluation and control unit in the portable unit uses, for example, an average value for the altitude of a multistory car park floor level to convert the determined altitude difference to the floor level difference. By way of example, the portable unit is in the form of an electronic vehicle key. The first time may, for example, be defined by a locking process of the parked vehicle. The second time may, for example, be defined by a control action which can be carried out via the portable unit. The control action comprises, for example, a predeterminable number of operations or one operation for a predeterminable time period of at least one control element which is arranged on the portable unit. In order to ensure that the vehicle can be found only by the person with the key, the communication path can, for example, allow only coded information transmission between the vehicle-end unit and the associated portable unit.
In a further refinement of the apparatus according to the invention, the vehicle-end unit and/or the portable unit have/has means for temperature compensation. This advantageously makes it possible to avoid temperature influences affecting the measurement of the air pressure.
In order to determine the precise vehicle position on the correct floor level once that floor level has been found, the apparatus according to the invention can be combined with means which allow two-dimensional location of the vehicle in a large parking lot or on one floor level of a multistory car park or an underground garage.
There are now various possible ways to refine and to develop the teaching of the present invention in an advantageous manner. For this purpose, reference is made on the one hand to the dependent claims and on the other hand to the following explanation of embodiments. The advantageous refinements which result from any desired combination of the dependent claims should also be included.